This invention relates to battery caps, and particularly to a battery cap which readily permits visual determination of the state of the battery fluid level and density without requiring removal of the battery cap itself.
Battery caps in the past have required removal of the battery to determine liquid level, and physical removal and sampling of the electrolyte to determine its condition.
There are battery cap constructions which permit through a transparent window a visual determination of the state of the battery without removing the cap. My copending application Ser. No. 522,529 filed Aug. 12, 1983, shows the use of a transparent window in a battery cap. Such use is shown in patents such as Sinclair No. 3,170,325 and Gosheff No. 2,484,163.
Other battery cap designs which are of interest with respect to this construction are shown in the Malone patent No. 3,893,339, and in the Sakamoto patent No. 3,895,964. The latter shows a floating ball which indicates the level of the electrolyte in the battery.
The above mentioned subject devices do have drawbacks with respect to either the possibility of misalignment and sticking of the floats, as well as the limitations with respect to the length of upward and downward travel of the elements to indicate the state of the electrolyte.